You should keep a few electrolytic caps handy, because the ones right next to the tubes on your PCB will die young...

Since your PCB is already made, I would recommend you mount the vertical electrolytic capacitors on the bottom side of the board to keep them as far away from the radiated tube heat as possible. You maybe Ok top mounting the two smaller vertical electrolytic capacitors that are the furthest away from the tubes as it is hard to tell how close they actually are in the picture. If you choose to mount them on the bottom be careful about polarity when installing. Mickeystan

The caps go on the other side.............. of the PCB. I check component spacings and count, look for missing components prior to etching the PCB's. I use the brittle green florist foam to push the leads into to do a mock-up.
Example of the KEG-EAR amp in process attached.....